Process of sedimentation



C. H. NORDELL.

PROCESS OF SEDIMENTATION.

APPLJCATlON FILED FEB. 16, 1920.

1 ,400,622, Patented Dec. 20, 1921.

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UNITED STATES," PATENT, OFFICE] CARL E. NORDELL, 0F INDIANAPOLIS, INDIA NA, ASS IGIIOR OF ONE-HALF T0 WILLIAM J. KENNEY, OF CHICAGO, ILLINOIS.

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Specification of Letters Patent. Patented, Dec. 20, 1921.

Application filed February 16, 1920. Serial No. 859,012.

To all whom it may concern:

Be it known that I CARL H. NORDELL, a citizen of the United tates, and resident of Indianapolis, inv the county of Marion and State of Indiana, have invented certainnew and useful Improvements in Processes of Sedimentation; and I do hereby declare that the following is a full, clear, and exact descri tion thereof.

y invention relates to new and useful improvements in the method of separating sediment from liquids in which it is held in suspension. The primary object of this invention is to provide a new method of withdraw'in from a body of li uid which is be-. ing sett ed, the clearest portion of the supernatant liquid and the most concentrated layer of sediment, without disturbance of the central zone between them. By the use of the process to which the invention pertains, the escape through the draw-01f of liquid insufiiciently sedimented or sludge or sediment insufiiciently concentrated, is prevented, that is to say short circuiting of liquid from inlet to outlet without a proper interval of detention obviated.

With. the foregoing general object, and

the obvious advantages to be derived therefrom in view, the invention resides in certain novel combinations and originalities of steps which may be carried out in connection with various forms of mechanism one of which is illustrated in the accompanying drawings wherein:

Figure 1, represents a vertical sectional view of a sediment tank constructed to carry out my improved process, and

Fig. 2, is a horizontal section View through this sedimentation tank.

Referrin more particularly to the drawings the i1 ustrated apparatus for carrying out the invention comprises a suitable container or tank 1, having a bottom 2 and top 3. The side wall of the tank, which is preferably cylindrical, is provided with an in of the tank as shown in the dot and dash line in the last mentioned figure. A similar action may be procured, however, by such mechanical means as stirring.

Superimposed within the container or sists of a sediment pipe 8 and a clear liquid pipe 9, the former of which has an opening 10 adjacent the upper surface of each plate 6 and the bottom 2. The liquid pipe 9 is similarly provided with openings 11, one of which is located adjacent the under side of each plate 6 and top 3.

In practice the liquid to be sedimented is introduced into tank 1 relativel slowly so as to cause the body of liquid 1n the tank to rotategently. In other words the rotation in most cases should be slow enough so that the liquid sweeping over the disks 6 is moving at a. rate below critical Velocity, that is to say slow enough to, prevent turbulent flow. n certain cases, however, this critical velocity may be exceeded without harm.

As the liquid rotates it is subjected to centrifugal force which causes it to rise or stand at a head or pressure increasing with the square of the distance from the center of the tank. The layers of liquid immediately adjacent to the disks 6, bottom 2, and top 3 are prevented by frictions from rotating at all, or they rotate only very slowly, and are therefore subjected to a much lesser degree of centrifugal force. As a consequence these layers of liquid are caused to flow to the center of the tank by the superior pressure existing in the rotating body of liquid in the regions out from the center. Therefore such layers of liquid adjacent to the disks fiow toward the center quite directly, and as the liquidadjacent to the under side of the disks 6 and top 3 is the clearest and that closest to the top of the disks 6, and bottom 2 is most loaded with sediment, and since such layers are more quickly removed through the outlet 7 than the central zone of liquid the chief object of the invention is realized. Short circuiting is also out to a minimum as the liquid must flow from the periphery of the tank to the center thereof in a spiral path for the reason that the centrifugal force imposed upon such liquid cannot readily short circuit, but must flow out through the full length of-the spiral path with its static head gra ually diminished by resistance to flow,

throughout the body of liquidby turbulent 7 cross currents. With this improved process the same phenomenon is encountered near' the surface of the disks as the liquid sweeps past them.- The particles of sediment are pushed away from the disks and the top and bottom of the container through the force just described, and if the liquid was homogeneous between the disks and top and bottom, the net result would be zero as the acceleration of sedimentation near the under side of the disks and top would be exactly counterbalanced by the retardation near the upperside of the disks and the bottom. The fact thatliquid near the upper side of the disks and bottom is loaded with sediment, however, increases its viscosity and results in quite a different distribution of velocities than occurs near the under side of the disks and the top, and in practice it is found that the acceleration of sediment is actually greater than the retardation that occurs near the surface of the disks.

Consequently that portion of the body of liquid which 1s adjacent to the top 3 and under side of the disks 6 is clear and is drawn off through the pipe 9. On the other .hand the portions of the li uid closest to the bottom 2 and the upper si es' of the disks 6 contain the concentrated sediment which is removed from. the tank 1 through the outlet pipe 8;

One quite important use of this improved process is found in sedimenting pulps and sludges which ordinarily require an appreciable period of quiescence before the flocs W111 draw together and settle (the pulps orsludges will not settle at all until these flocs. are formed and they will not form until the liquid is quiescent). It is difficult to have quiescent. liquid in a continuously operatedmembers,

I claim:

. 1. The method of sedimentation which consists in rotating a body of liquid in contact with a series of retardation members arranged one above the other and extending transverse to the axis of rotation so as to retard the motion of those portions of said body in contact withsaid members relatively to t e remainder, and withdrawing clarified liquid from the vicinity of the under side of each of said members and sludge from the vicinity of the upper side of each of said members.

2. The method of sedimentation which consists in rotating a body of liquid in contact with a series of retardation members arranged one above the other and extending transverse to the axis of rotation so as to retard the motion' of those portions of the-liquid in contact with said members relatively to the remainder, withdrawing clarified liquid from the vicinity of the under side of each of said members at said axis, and withdrawing sludge from the vicinity of the upper side of each of said members.

3; The method of sedimentation which consists in rotating a body of liquid in contact with a series of retardation members arranged one above the other and extending transverse to the axis of rotation so as to retard the motion of those portions of the liquid in contact with said members relatively to the remainder, withdrawing clarified-liquid from the vicinity of the under side of each of said members at said axis,

and withdrawing sludge from the vicinity of the upper side of each of said members at said axis.

4. A system of sedimentation comprising a container closed at the top, a plurality o transverse retardation members arranged within the container and spaced apart from the "top and the bottom of the container,

means for producing a vortex action in contact with said members and the top and bottom of the container of liquid to be sedimented, and means for withdrawing clarified 1i uid from the vicinity of the under side oi the top and the under side of each of said members, and means for withdrawing sludge from the vicinity of the bottom of the container and the upper side of each of said members.

5. A system of sedimentation comprisin a plurality. of retardation members arrange one above the other, means for rotatin a body of liquid about a vertical axis an in contact with said members, and means for withdrawin clarified liquid from the vicinity of t e under side of each of said and means for withdrawing sludge from the vicinity of the upper side of each of said members.

6. A system of se i enta i n eenp s a plurality of retardation members arranged one above the other, means for rotating a body of liquid between and in contact with said members, means for withdrawing clarified liquid from the vicinity of the under side of each of said members at the axis of rotation, and means for withdrawing sludge from the vicinity of the upper side of each of said members.

7. A system of sedimentation comprising a plurality of retardation members arranged one above the other, means for rotating a body of liquid between and in contact with said members, means for withdrawin clarified liquid from the vicinity of the un er side of each of said members at the axis of rotation, and means for withdrawing sludge from the vicinity of each of said members at said axis.

8. A system of sedimentation comprising a container, a plurality of transverse retardation members arranged one above the other in said container, said members being smaller than the cross-sectional area of the container so as to leave a space between them and the sides of the container, means for rotating a body of liquid in said container in contact with said members, means for withdrawing clarified liquid from the vicinity of the under side of each of said members, and means for withdrawing sludge from the vicinity of the upper side of each of said members.

In testimony that I claim the foregoing I have hereunto set my hand at Milwaukee,

in the county of Milwaukee and State of Wisconsin.

CARL H. NORDELL. 

